Illinois Fruit and Vegetable News:

A Newsletter for Commercial Growers of Fruit and Vegetable Crops
A Publication of University of Illinois Extension and the College of Agricultural, Consumer, and Environmental Sciences

Vol. 9, No. 4, April 23, 2003

"We are what we repeatedly do. Excellence, then, is not an act, but a habit." --Aristotle

Address any questions or comments regarding this newsletter to the individual authors listed after each article or to its editor, Rick Weinzierl, 217-333-6651, weinzier@uiuc.edu. To receive email notification of new postings of this newsletter, call or write the same number or address.

This issue's words of wisdom ... which usually means the jokes ... are at the end of newsletter ... check the last page.

In This Issue:

Crop Reports (from Elizabeth Wahle and Maurice Ogutu)

Degree Day Accumulations

Notes from Chris Doll (fruit development, plasticulture strawberries, and thinning)

New Registrations (Section 18 for Spartan 75 DF in horseradish inIllinois)

Upcoming Meetings (Agricultural Plastics Conference, August 16-19, Grand Rapids, MI)

Fruit Production and Pest Management (More on codling moth control, Warrior?s use in tree fruits, miscellaneous fruit insect notes)

Vegetable Production and Pest Management Update (Glyphosate confusion, methyl bromide replacements, and Admire for cucumber beetle control)

University of Illinois Extension Specialists in Fruit & Vegetable Production & Pest Management

Crop Reports

In the south and southwest, the region received scattered rain showers the latter half of last week and over the weekend.  All areas of the region report good bloom in all tree fruits.  Temperatures dipped below freezing in most areas of the region on the 10th of April, but not low enough to cause much damage.  There will be an apricot crop this year, with trees in the western portion of the area at shuck split.  I received several reports from growers of bloom thinning of peaches during pruning and initial reports that chemical thinning of apples has begun.  The western portion of the region has begun to catch coddling moths in traps.  Counts so far have not been consistent or high enough to set a biofix date, but significant captures are expected  in the very near future.  The strawberry crop looks good in the region, both matted row and plasticulture.  Vegetable producers have begun early plantings, with reports of sweet corn plantings started as early as March 24 in the northwest portion of the region. 

Elizabeth Wahle (618-692-9434; wahle@uiuc.edu)

In northern Illinois, day temperatures have reached  the upper 50s to lower 60s, and cloudy days, scattered showers, and night temperatures in the upper 30s to lower 40s have been common.  Tillage operations are going on in some farms. The monthly rainfall total in most parts of northern Illinoisis about 1 inch.  Most apples are at the  half-inch green to tight cluster stages as of April 22.  Pears are in the green cluster to white bud stages.  Apple scab and powdery mildew control spray programs are going on, spotted tentiform leafminer traps are up in most orchards, and growers  have embarked on European red mite, San Jose scale, and adult spotted tentiform leafminer control spray programs.  Grapes are still dormant, and spray programs for anthracnose, European red mites, and scales are going on.  Currently we have not received any report on flea beetles or climbing cutworms in vineyards.  Raspberry canes have green tips, and some growers are still going on with dormant season spray schedules.  Planting of cool-season vegetables such as potatoes, cabbage, broccoli, and onions has begun.

Maurice Ogutu (708-352-0109; ogutum@mail.aces.uiuc.edu)

Projections for degree day accumulations two weeks into the future are derived by adding historic averages for degree days for the next two weeks to the actual current total listed for each location (April 20 in this instance).

Kelly Cook (217-333-6651; kcook8@uiuc.edu; Rick Weinzierl (217-333-6651; weinzier@uiuc.edu)

Notes from Chris Doll

A close call temperature-wise on the morning of the 23rd ... the recorder in the orchard (at 5 feet elevation) dropped to 36 degrees, and floating row covers on the strawberries were frozen solid. But, optimism prevails and little damage should have occurred.

Rainfall for the month is 1.8 inches and the DD50 accumulation through 4/22 is 290.  The Back 40 now has apples up to 7.5 mm diameter for the early bloomers, with Reds and Goldens at 3.5 to 5.5 mm.  Some flowers are still open due to the variety mix, but even Jonagold and Jonathan have numerous flowers.  Fruit set appears to be good. Peaches are in shuck split to shuck off and they too appear to have set more than will be needed.  Early blooming Asian pears are heavy, and late bloomers are light from the freeze of the 14th.  Sweet cherries and tart cherries also are light due to the freeze.

Crop development in Unionand Jackson counties is only a few days ahead of Edwardsville, so the apples should be at thinning size, and the shucks are off the peaches.  No one has reported codling moth catches from the Illinois side of the river, so I went to Marthasville, Missouri yesterday (4/22) and found traps with up to 9 moths for the first catch of the year. (Marthasville is 14 miles south of I-70, out west of St. Louis.)

The only disease found on tree fruits has been a trace of powdery mildew.  Insect findings include some rosy apple aphids, European Red Mites, and white apple leafhoppers.  Fireblight sprays in the area have been relatively easy to time during the period of light to moderate showers.  Time will tell if the computer programs and human judgment are winners.

I've seen 4 fields of plasticulture strawberries in the past week and there is quite a variation in vigor and bloom, with most of it depending on the soil type and date of planting.  In general, the crown and bud set appear to less than last year, and this might be attributed to later planting and a colder October.  Harvest is at least a couple of weeks away.  Matted row plantings are looking pretty good.

Apple thinning time is either here or fast approaching for this area.  Our Illinois Spray Guide has a brief description of thinning principles, a fairly easy to use chart on thinner rate by variety (page 40), and a helpful chart (page 41) for calculation rates of NAA by commercial product.  Dr. Mosbah Kushad gave a great summation of the practice at the 2002 Fruit Schools, and some of it came from the "Apple Thinning Guide" written by Phil Schwallier of Michigan State University and published by the Great Lakes Publishing Company.  Specifics for being aggressive, moderate and mild in the approach are given for beginning at petal fall , at early fruit set and late fruit set.  Too much to write here, so check the copy.  I also like to read the thinning section in the Penn State Fruit Production Guide.  Dr. Rob Crasweller of Penn State has said that "weather conditions immediately prior to and after application of thinners are probably more important than size of fruit" (Fruit Times, Vol. 22, No. 15).  In other words, cold cloudy weather is adverse, and lots of cloudy weather ahead of application can make the trees more susceptible to reaction.

There is still time to graft trees, score for fruit set, prune newly set trees, begin tree training with toothpicks or clothes pins, hanging weights or other tie-down materials.

Chris Doll

New Registrations

Spartan Receives Section 18 Specific Exemption for Use on Horseradish in Illinois

The US Environmental Protection Agency on April 1granted a Section 18 specific exemption for the use of Spartan 75 DF (sulfentrazone) herbicide for the control of broadleaf weeds in horseradish.  Spartan is especially useful for controlling pigweeds, water hemp, eastern black nightshade, yellow nutsedge, and morningglories.  Spartan should be applied at 5.3 ounces of product (0.25 lb active ingredient) per acre after horseradish planting but at least five days before horseradish emergence.  Spartan can be tank mixed with Goal (oxyfluorfen) to broaden the spectrum of grasses and broadleaf weeds controlled,  but the tank mix may increase the likelihood of horseradish injury.

(John Masiunas (masiunas@uiuc.edu)

Upcoming Meetings

The American Society for Plasticulture is holding the 31^st annual Agricultural Plastics Congress at the Crowne Plaza Hotel in Grand Rapids, Michigan, August 16-19, 2003.  For more information check their web site at http://www.plasticulture.org/ or call 814-238-7045.

Fruit Production and Pest Management

More comments on codling moth control

Questions on application timing and selection of insecticides for codling moth control have been numerous of late.  Here?s my best shot at a brief explanation. 

• If you do not use pheromone traps, you?re in the dark and just guessing about when to spray ... not wise.  Check previous issues of this newsletter for sources of traps and lures and directions on their use.  That said, if you refuse to use traps and prefer unwise guessing as a way to plan the application of hundreds of dollars worth of insecticides per acre, begin your codling moth spray program about 12 to 14 days after your petal-fall insecticide application.
• Catching codling moths in traps provides a ?biofix? ... that means you know that a significant number of moths are flying and laying eggs, and that if you start counting degree days you can know when a spray needs to be in place to kill the larvae before they tunnel into the fruit.  What constitutes a significant number of moths is a bit debatable, but generally (and pretty conservatively) the numbers agreed to are 3 moths per trap per week or a total of 5 moths per trap (even if it takes more than a week to reach the total of 5). Check traps at least twice weekly and begin counting base 50 degree days as soon as traps catch the prescribed number of moths.  Eggs will begin hatching at 240 degree days after they?re laid on foliage, twigs, or fruit, and larvae will enter fruit soon after they hatch.
• Spray timing: For all the organophosphates such as Guthion, Imidan, and diazinon, and the pyrethroids such as Asana, Danitol, and Warrior, none of which kill eggs, the recommended timing for applications is just before egg hatch, so right around 220 to 240 degree days.  This is ?on time? and provides maximum residues on fruit as codling moth larvae become active.  Labels for products that have some ovicidal (egg-killing) activity and some of the insect growth regulators call for applications a little earlier, beginning at around 150 degree days after biofix.  Insecticides with labels that advise this earlier timing include Intrepid, Confirm, Esteem, Assail, and Avaunt.  Don?t agonize too much about these differences in application timing ... the real key is to make sure you check traps and know when moth flight is underway, then make sure you get your sprays on before egg hatch begins.
• Insecticide choice: If you controlled codling moth successfully with Guthion and Imidan last year, you should be able to use these two insecticides along with all the alternatives in some pattern of rotation to control codling moth this year.  The alternatives that cause the fewest problems in terms of disrupting natural control of red mites include Assail, Esteem, Intrepid, Confirm, and Avaunt.  Alternatives that also kill predaceous mites and can trigger red mite outbreaks include Asana, Danitol, and Warrior.  If you have experienced control failures with Guthion or other organophosphates, available data suggests that you should NOT expect any of the following insecticides to be very effective: Guthion, Imidan, Diazinon, Asana, Danitol, Warrior, Intrepid, and Confirm.  Use Assail and Esteem for early-season codling moth control.

Rick Weinzierl (217-333-6651; weinzier@uiuc.edu)

Warrior insecticide and fruit crops

Labels for the insecticide Warrior (lambda-cyhalothrin) were expanded earlier this year to include use on apples and stone fruits (as well as tree nuts).  I?ve seen very little data on the likely effectiveness of Warrior against tree fruit insects, so answering questions about its fit in Illinoistree fruit pest management is a little difficult.  Based on its performance in vegetable crops and its pyrethroid structure, here?s what I think you can expect ...

In stone fruits, particularly peaches, Warrior is likely to provide control of stink bugs, plant bugs, and Oriental fruit moth at a level comparable to or a little better than that provided by Pounce, Ambush, or Asana.  It almost certainly will not control European red mites and instead almost certainly will ?flare? mite problems by killing predaceous mites ... this outcome would be no different than that expected from use of Pounce, Ambush, or Asana.  If Oriental fruit moth populations are resistant to the pyrethroids permethrin (Pounce or Ambush) or esfenvalerate (Asana), one should expect them to be resistant to Warrior as well.  We have not observed pyrethroid resistance in Oriental fruit moth in Illinois, but growers should be aware that to delay resistance development the exclusive use of pyrethroids is discouraged.  Switching from Pounce or Asana to Warrior will do no good in delaying or managing resistance.  So, until we know more details, the bottom line for stone fruits is that Warrior might be used instead of Pounce, Ambush, or Asana for control of Oriental fruit moth, stink bugs, or plant bugs with the expectation that control, resistance management (or lack thereof), and mite outbreaks will be roughly the same. 

In apples, Warrior?s label lists codling moth, apple maggot flies, plum curculio, leafhoppers, and aphids among target pests.  Unless I learn of some unique benefit provided by Warrior in apples, I am hard-pressed to find a reason to recommend it for control of any of these pests (just as I am hard-pressed to recommend other pyrethroids against these pests in apples).  Again, one has to predict that Warrior will trigger outbreaks of European red mite by failing to kill these mites while killing their predators.  Other products that do not flare mites are available and effective for control of the pests listed above, so inserting Warrior into an apple spray program does not seem wise in most instances.  The obvious question that Illinoisapple growers might ask is ?Would Warrior be effective against organophosphate-resistant codling moths??  Unless small-plot trials show otherwise, I doubt it.Washington and Californiaresearchers (Dunley and Welter) found that organophosphate-resistant codling moths showed cross resistance or multiple resistance to Asana and Danitol (two pyrethroids) as well, and these pyrethroids (Asana and Danitol) have been ineffective for codling moth control in Illinoisorchards where Guthion resistance has developed.  So, the bottom line for apples is that Warrior seems to offer little or no unique benefit and likely would contribute to mite outbreaks.  Unless it proves to be effective against organophosphate-resistant codling moths in early season small-plot trials, I would not recommend its use in most Illinoisapple orchards.

Rick Weinzierl (217-333-6651; weinzier@uiuc.edu)

Miscellaneous comments on fruit insects

• Apple growers who use Assail, Avaunt, or Actara at petal fall or first cover for control of other pests should expect control of white apple leafhopper as well ... don?t add Provado to the spray tank for this insect if you?re already using these products.
• The best timing for sprays intended to control the foliar form of grape phylloxera is at bloom and about 10 days later (no problem with bees in this situation, they don?t pollinate grapes or forage in grape flowers).  Thiodan and Danitol are effective for this use, but Thiodan will injure several grape cultivars.  Check your small fruit spray guide and the Midwest Small Fruit Pest Management Handbook for details. 
• Stone fruit growers should check pages 26-27 of the 2003 Illinois Tree Fruit Spray Guide for comments on timing and selection of insecticides for lesser peachtree borer control ... early to mid-May is often the right time for trunk sprays (and pheromone traps are available to determine the best timing).

Rick Weinzierl (217-333-6651; weinzier@uiuc.edu)

Vegetable Production and Pest Management

Having Many Glyphosate-Containing Products Results in Price Breaks But Confusion

Glyphosate (i.e. Roundup) is widely used in fruit and vegetable crops for as a nonselective herbicide for control of emerged weeds either in rows of trees or vines or for stale seedbed treatments before planting vegetables.  In September 2000, Monsanto?s U.S.patent on glyphosate expired resulting in an increase in the number of glyphosate containing products available.  These new products include Acquire, Buccaneer, ClearOut 41, Credit Duo, Gly-Flo, Glyphomax, Glyphosate, Mirage, Rattler, Roundup UltraMax. and Touchdown IQ.  This wide array of glyphosate contain products has provided some important price benefits but also has caused confusion.

James Martin and J. D. Green of the University of Kentucky have written an excellent article comparing these products (http://www.uky.edu/Ag/Agronomy/Weeds/ ). In this article and accompanying tables they sort out how these glyphosate containing products differ.  The first way the products differ is in the concentration of the active ingredient (generally expressed as acid equivalents).  Most products contain 3 lbs of acid equivalent/ gallon but there are exceptions.  For example, Gly Star 5 contains 4 lbs of acid equivalent/ gallon, Roundup UltraMAX contains 3.73 lbs acid equivalent/ gallon, and Roundup Weather MAX contains 4.5 lbs acid equivalent/ gallon.  When determining price make sure to compare like amounts of the acid form of glyphosate.

Secondly, the type of salt used in the glyphosate formulation can vary.  The most common salt is the isopropylamine but Touchdown Iq uses the diammonium and Roundup Weater MAX uses the potassium salt.  The salt used in the formulation can effect performance such as rainfastness and absorption into the plant.  It will also impact on the amount of active ingredient in a formulation.  This is why it is important to compare acid equivalents of glyphosate when selecting a product.

The use of adjuvants also varies depending on the glyphosate containing product.  Most glyphosate containing products indicate that ammonium sulfate (AMS) can be added as an adjuvant.  AMS can improve the activity of glyphosate when it is tank mixed with some soil-residual herbicides, where weeds are not actively growing, where water hardness exceeds 500 ppm calcium or magnesium, or where problem weeds such as velvetleaf are present.  Recommendation on using a surfactant vary depending on the glyphosate containing product.  Some labels allow additional surfactant to be added, other glyphosate containing products require adjuvant, while products with unique surfactant systems (i.e. Roundup Ultra) do not allow additional surfactant.

Several Universities have compared different glyphosate containing products.  All glyphosate products should provide adequate weed control if applied at the recommended rate to actively growing weeds at the proper size.  Any differences in efficacy have generally been small and variable.

John Masiunas (masiunas@uiuc.edu)

Research on Methyl Bromide Replacements

Methyl bromide has been used by some Illinois growers before planting high value crops such as strawberries.  It is particularly important for California and Floridaproduction systems with approximately 85% of the total methyl bromide used in the U.S. used in those two states.  Methyl bromide has been classified as an ozone-depleting substance and its use in the U.S. will be phased out by 2005.  Thus it is important to find alternatives to methyl bromide.

In the most recent issue of HortScience [38(1):55-61], Steve Fennimore, M. J. Haar, and H. A. Ajwa from the University of California - Davis and the U.S.D.A. Agriculture Research Service report the results from a study of the weed control effectiveness of several methyl bromide alternatives used in strawberry.  They evaluated InLine (60% 1,3-D plus 32% chloropicrin), Telone C35 (62% 1,3-D plus 35% chloropicrin), CPEC (95% chloropicrin), Vapam HL (42% metam sodium) either applied through a drip irrigation system or shank injected.

One important difference between products was in cost.  The table lists the prices for the products in California.  In general the more effective treatments (see below) are going to be comparable or less costly than are current applications of methyl bromide + chloropicrin.

Fumigation through drip irrigation or with shank injection for chloropicrin (CPEC) alone, InLine or Telone C35 were highly active on weeds that methyl bromide readily controls - those without hard seed coats such as common chickweed.  Fumigation through drip irrigation lines with InLine may provide better weed control than shank injection of Telone C35.  Under the conditions of their study, Fennimore and colleagues felt that the application of Vapam after InLine or CPEC was not justified.

John Masiunas (masiunas@uiuc.edu)

Admire for cucumber beetle control

Controlling striped and spotted cucumber beetles to prevent outbreaks of bacterial wilt is especially important in cucumbers and muskmelons ... the threshold for application of foliar insecticides early in the season is 0.1 to 1 beetle per plant.  The Midwest Vegetable Production Guide and the Illinois Agricultural Pest Management Handbook list insecticides and rates for foliar sprays.  Many growers have used Furadan for several years as a soil insecticide or transplant drench for systemic uptake and cucumber beetle control.  Recently the insecticide Admire (imidacloprid) was registered for the same purpose.  Band applications, in-furrow sprays, transplant drenches, and side-dress applications have all proven effective for cucumber beetle control ... check the references listed above and the product label for application details.  Where Furadan or Admire are used for cucumber beetle control, be sure to scout fields anyway after transplanting or as seedlings emerge, because sometimes beetle infestations can cause significant losses before systemic uptake is sufficient to provide control.  A single foliar application of insecticide may be warranted where beetles are numerous initially despite the use of Furadan or Admire.

Rick Weinzierl (217-333-6651; weinzier@uiuc.edu )

This issue's Words of Wisdom ...

Some humor from a presentation by Roger Carter of Clayton, Louisiana, at a recent meeting of CAST ...

• You can duplicate the warmth of a feather mattress by climbing into a plastic garbage bag with several geese.
• Anything worth doing is worth doing slowly.  (Gypsy Rose Lee)
• The person with the least expertise has the most opinions.
• Advice to young farmers: You will be poor and unhappy and frustrated until you farm for 25 years; then you?ll get used to it.
• Law of Avoiding Overselling: When putting cheese in the mouse trap, always leave room for the mouse.
• "Her hair glistened in the rain ... like nose hair after a sneeze."

University of Illinois Extension Specialists in Fruit and Vegetable Production & Pest Management

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